1. Field of the Invention
The present invention relates to an apparatus and a method for performing a treatment by supplying a process liquid to process objects such as semiconductor wafers and LCD glass substrates.
2. Background Art
In manufacturing semiconductor devices, a liquid treatment such as an etching treatment or a cleaning treatment is performed to process objects such as semiconductor wafers or LCD glass substrates by supplying a process liquid such as a chemical liquid or a rinse liquid into a process bath holding the process liquid in which the process objects are immersed.
JP10-229065A discloses a liquid treatment apparatus including process liquid discharge ports, which are disposed on opposite corners of a process bath accommodating process objects therein, and which alternately discharge a process liquid. The process liquid discharge ports arranged at one of the corners firstly discharges the process liquid. Thus, a process liquid convection is generated in the process bath, so that particles flow together with the convection and are discharged from the process bath together with the process liquid overflowing from the process bath. At this time, a stagnation area, where the velocity of the process liquid flow is low and thus particles may stagnate, exists in the process bath. Thus, before the stagnation of the particles occurs, the discharge of the process liquid from the process liquid discharge ports at the one corner is stopped, and the discharge of the process liquid from the process liquid discharge ports on the other corner is started. The discharge of the process liquid from the discharge port at the other corner causes a new convection in the process bath, and the newly generated convention collides with the existing convection which has been generated by the discharge of the process liquid from the discharge ports at the one corner. Then, a disturbed flow of the process liquid caused by the collision of the convections moves the process liquid in the stagnated area. The process liquid thus moved flows with a new convection, and is discharged from the process bath together with the process liquid overflowing from the process bath. In this manner, the liquid treatment is performed while preventing re-adhesion of the particles to the process objects by periodically removing the stagnated area.
However, the stagnation occurs at the same location, and the process liquid does not flow through the location at a sufficiently high velocity. Further, the process liquid is not discharged directly toward the process objects. These may cause non-uniform treatment of the process objects. Such a problem is more serious when the liquid treatment is an etching treatment.
JP6-204201A discloses a liquid treatment apparatus that performs a chemical liquid treatment by supplying a chemical liquid to a process bath accommodating process objects, and thereafter performs a rinse treatment by supplying a rinse liquid to the process bath. Process liquids are supplied to the process bath from two supply nozzles arranged at bottom portions of the process bath. After the chemical liquid treatment, the rinse liquid is supplied from the supply nozzles so that the chemical liquid held in the process bath overflows therefrom, thereby the chemical liquid held in the process bath is replaced with the rinse.
In a preferred embodiment, the plurality of process liquid supply nozzles are divided into a first group and a second group, the process liquid supply nozzles belonging to the first group are arranged at different levels on one side of the process object, and the process liquid supply nozzles belonging to the second group are arranged at different levels on another side of the process object. In this embodiment, the plurality of process liquid supply nozzles are preferably arranged so that the first group includes process liquid supply nozzles each located at a level corresponding to that of each of the process liquid supply nozzles belonging to the second group. The liquid treatment may be a treatment that treats the process object with a chemical liquid as the process liquid. The controller may be configured to control the process liquid supply valves so that one of the process liquid supply nozzles of the first group and one of the process liquid supply nozzles of the second group, which are arranged at the same level, simultaneously discharge the process liquid at least in a part of the plurality of process liquid supply periods. Alternatively, the controller may be configured to control the process liquid supply valves so that the following conditions are alternately achieved repeatedly at least in a part of the plurality of process liquid supply periods: a condition in which one of the process liquid supply nozzles belonging to the first group discharges the chemical liquid while the process liquid supply nozzle belonging to the second group arranged at a level corresponding to that of the one of the process liquid supply nozzles belonging to the first group does not discharge the chemical liquid; and a condition in which one of the process liquid supply nozzles belonging to the second group discharges the chemical liquid while the process liquid supply nozzle belonging to the first group arranged at a level corresponding to that of the one of the process liquid supply nozzles belonging to the second group does not discharge the chemical liquid. The liquid treatment may also be a treatment that treats the process object with a rinse liquid as the process liquid. In this case, the controller may be configured to control the process liquid supply valves so that, at least in one of the plurality of process liquid supply periods, one of the process liquid supply nozzles belonging to the first group discharges the rinse liquid while the process liquid supply nozzle belonging to the second group arranged at a level corresponding to that of the one of the process liquid supply nozzles belonging to the first group does not discharge the rinse liquid.